Field of Invention
In a vehicle such as a truck, a single power source, such as a battery, drives a plurality of circuits through a plurality of fuses. In a truck these plurality of circuits are used to power both the tractor and trailer(s). The trailer needs power for marker lights, brake lights, and various other systems. Each one of these branch lines, or circuits, on a trailer is identified by a unique color. The standard configuration is as follows:
WhiteGround return for all circuits on the towed vehicleBlackPower for the clearance, side marker & license plate lampsYellowPower for the left hand turn signal & hazard signal lampsRedPower for the stopping lamps and anti-lock devicesGreenPower for the right hand turn signal & hazard signal lampsBrownPower for the tail, clearance, side marker, and identificationlampsBluePower for auxiliary
One colored line and the white line (or ground return) line make up one circuit, so these seven lines make up six circuits. These six power lines and one ground line originating from the tractor are connected to the trailer through an industry standard SAE J560 (seven pin) connector, Surface Vehicle Standard SAE J560 Specification, Society of Automotive Engineers, Inc., June 1993. The primary purpose of these lines is to deliver power. However, they may also transmit data. An example of this is the anti-lock braking system (ABS).
For purposes of this disclosure, any device or system that transmits and/or receives data over the power lines, singularly or in combination, are herein referred to as Power System Communication Devices (PSCD). Furthermore, PSCD may be factory installed or may be retrofit in an after market installation.
The data transmitted by these PSCD may communicate collision avoidance data, anti-lock braking data, temperatures, tire pressures, and other data to the driver. Currently each PSCD manufacturer uses its own communications protocol, and no single industry standard has emerged.
In professional trucking applications, power system communication is desirable because the existing wire harness may be used and dedicated cables do not have to be routed throughout the vehicle. This is of particular concern if communication is required between systems on the trailer and systems in the tractor. In practice, most tractors are hitched to many different trailers. The standard SAE J560 (seven pin) connector serves to standardize the power connection and thus allows a tractor to be paired with any trailer.
Currently there is no provision for a standard data connection between the tractor and the trailer. It is not desirable to run “rogue” data connections between the tractor and the trailer because tractors and trailers would no longer be universally compatible. Because no standard exists, data connectors might be routed in different physical locations, have different connector types, or even different pin assignments. Therefore, to maintain the universal compatibility between tractors and trailers, it is highly desirable to use the exiting power system for communication.
Power system communication is also desirable in other articulated vehicle applications (such as but not limited too, boats trailers, campers, or car trailers, and other like towing applications) when communication is desired between a lead vehicle and a vehicle in tow. Although universal compatibility is not paramount in these other applications, it is still desirable to eliminate additional wires and connections if at all possible. By using the power bus for communication, the elimination of extra wires is achieved.
Because all of the circuits in a truck are ultimately tied together at the battery in the tractor, communications on the power lines is similar to a telephone “party line” where anyone who picks up their receiver will hear the conversations of everyone else who is talking on the receiver. Therefore, the potential exists for a PSCD from one manufacturer to interfere with the operation of another PSCD from a different manufacturer as they both communicate over the power lines. Interference can occur even if the two PSCDs are on different circuits.
This invention comprises a method of isolating the communications on multiple power lines of a tractor from one another without affecting the power transferred to the branch lines, or circuits for the purpose of generating multiple data buses. This will be accomplished though the use of one or more data filters. For purposes of this disclosure, the term “data filter” refers to one or more inductors, resistors, capacitors, transistors, and/or any combination of like parts known in the art with the purpose of filtering the data communications while passing power through it. Furthermore, this invention isolates the data on the tractor from any trailer or trailers that are electrically connected to the tractor while still allowing the power to be transferred to the branch lines, or circuits. Furthermore, this invention isolates the data on each of the trailers that are electrically connected to each other while still allowing the power to be transferred to the branch lines, or circuits.
This invention allows the number of PSCD that can be attached to the tractor and/or trailer(s) to be increased. It prevents interference between multiple PSCDs. It allows for the use of multiple communication protocols among the different PSCDs sharing the power lines. This is done without alteration to the existing tractor's or trailer's wiring and thus adhering to the SAE J560 standard. This invention also adheres to Safety Standard 121 that requires an anti-lock brake communication signal between the tractor and trailer. This invention also relates to the selected isolation of portions of the power lines.
Related Prior Art:U.S. Pat. No.Inventor3,842,397Sindle3,944,981Akita et al3,975,708Lusk et al4,015,232Sindle4,278,962Lin4,349,823Tagami et al4,626,849Sims4,714,912Roberts et al4,801,938Holmes5,528,217Adams5,734,357Matsumoto et al6,127,939Lesesky et al